Differential feed device for a sewing machine



March 23, 1965 l.. BONO 3,174,449

DIFFERENTIAL FEED DEVICE FDR A SEWING MACHINE Filed oct. 1e, 1961 United States Patent O t 3,174,449 DHFFERENTIAL FEED DEVlCE FOR A SEWING MACHNE Luigi Bono, Pavia, italy, assignor to Necchi Societa per Azioni, lavia, Italy Filed Uct. 16, 1961, Ser. No. 145,170 Claims priority, application Italy, Apr. 11, 1961, 646,349 Claims. (Cl. 112-209} This invention relates in gen-eral to new and useful improvements in sewing machine construction, and more particularly relates to a device for controliing the direction and amplitude of the horizontal oscillations of the two feed dogs of a differential-feed sewing machine.

In accordance with this invention, it is proposed to provide means for pnesetting lthe horizontal oscillations of one of the feed dogs las a function of the oscillations of the other of the feed dogs, and at the same time, makes it possible to vary by the same amount the amplitude of the horizontal oscillation of the two feed dogs and to reverse at any time the direction of these oscillations.

Another object of .this invention is to provide means for controlling the amplitude of the horizontal oscillations of the two feed dogs of a differential-feed sewing machine and including means to vary at any time during the operation of the sewing machine the horizontal oscillations of one of the feed dogs Awith respect to the other of the feed dogs.

Another object of this invention is to provide a novel means for varying the lhorizontal oscillation of feed dogs of a differential feed sewing machine wherein the overall amplitude of the horizontal oscillation of the feed dogs is .controlled by a mechanism in accordance with the stitch length, and there being provided additional means for controlling the horizontal oscillation of one of the feed dogs with respect to the other of the feed dogs by means of a foot control pedal.

A further object of this invention is to provide novel means for oscillating feed dogs of a differential feed sewing machine, the feed dogs being constantly driven from a rotating shaft by means of a pair of cams connected to `linkages which are, in turn, connected to the feed dogs, and ther-e being provided means for selectively varying the effective lengths of the linkages so as to vary the effect of the ycams on the oscillatory movement of the feed dogs.

With the above and other objects in view that will hereinafter app-ear, the nature of the invention will be more clearly understood by reference to the following detailed description, the 4appended claims and the sevyeral views illustrated in the accompanying drawing:

In the drawing:

lFIGURE. 1 is a schematic perspective view showing a sewing machine of the general type to which the present invention relates, the sewing machine being equipped with the feed dog control system which is the subject of 'this invention.

` FIGURE 2 is a perspective view, with parts broken away and shown in section, and other parts being separated, of the specific feed dog control device.

`FIGURE 3 is a schematic view showing slight modiications of the device.

-FIGURE 4 is an enlarged fragmentary perspective view includes an arm 1 supported from a base 2 by means of a column 3. The actuation of the sewing machine is controlled in the traditional manner by an electric motor (not shown) by acting, for instance, on a pedal 4 mounted on the support 5 of the sewing machine.

A shaft (not visible in the drawings) rotates within the arm 1 and transmits to the conventional needle bar 6 the reciprocating movement necessary in order for a needle 7 carried by the needle bar 6, upon penetrating into the thickness of the fabric and into a hole 8 of a needle plate 9, to effect the formation of the required stitch, in collaboration with well known stitch-forming members (not shown) arranged below the base 2. In addition to the hole 8, the needle plate 9 has slots 10 and 11 formed therein within which feed dogs 12 and 13 are movable. The feed dogs 12 and 13 have arms 14 and 15, respectively, which are secured to supports 16 and 17, respectively, which extend below the base 2.

In accordance with the invention, the means for raising and lowering in synchronism the feed dogs 12 :and 13 within the slots 10 and 11 include a connecting rod 18 which receives the necessary motion from a cam 19 which is rigidly fastened to a shaft 20 suitably journaled in and rotating below the base 2. The end of the connecting rodA 18 remote from the shaft 21D is pivoted to an arm 21 of a shaft 22 which, in turn, is supported by the base 2. The shaft 22 carries two arms 23 and 24 which are parallel to each other and to which there are pivotally connected connected connecting rods 25 and 26, respectively. The connecting rods 25 and 26 are, in turn, pivotally connected to the end 27 of the support 16 and the end 28 of the support 17, respectively. Thus, as the shaft 20 rotates, the connecting rod 13 is moved to effect the rocking of the shaft 22 with the resultant raising and lowering of thev supports 16 and 17 in timed relation to the movement of the needle bar 6.

The device for controlling the amplitude and direction` of the horizontal oscillations of the feed dogs 12 and 13 Within the slots 10 and 11 include two connecting rods 29 and 30 which surround cams 31 .and 32, respectively, keyed on the rotating shaft 20. The connecting rod 29 is operatively connected with the support 16 of the feed dog 12 and with a lever 33 which is rigidly attached to a pin 34, the pin 34 being supported in the base 2 of the sewing machine. Similarly, the connecting rod 30 is operativelyV connected with the support 17 of the feed dog 13 and with a lever 35 which can be oriented around `a pin 36 which is supported in the base 2 coaxially with the pin 34.

The lever 35 is pivoted to the pin 36 indirectly by way of the connecting member represented by an arm 70 which is pivoted to the pin 36 and towhich the lever 35 can be fastened in a manner to be described hereinafter.

In accordance with the preferred embodiment of the invention, the operative connections between the connecting rod 29, the support 16 and the lever 33 are made inV the manner shown in FIGURE 2. An end 37 of the support 16 is pivotally connected to an arm 38 of a shaft 39 which the supported in the base 2 of the sewing machine in any suitable manner. The shaft 39 has an armV 41B to which there is pivoted an end 41 of a rod 42. The opposite end of the rod 42 carries two pins 43 and 44. The connecting rod 29 is pivotally connected to the rod 42 by means of the pin 43.

The pin 44 has pivoted thereto an end of a small lever 45, the other end of which is pivoted on a pin 46. The pin 46 is, in turn, rigidly carried by the lever 33. The actions of the pin 44 and the lever 33 coincide with the center point of oscillation of the pin'44 about the pin 46.

In a similar fashion, the operative connections between the connecting rod 30, the support 17 and the lever 35 can be made in the manner best shown in FIGURE 2.w

As is shown in this figure, an end 47 of the support 17 is pivotally connected to an arm 48 of a shaft 49 which is supported in the base 2 in any suitable manner and parallel Vto the shaft 39. The shaft 49 has an arm to which there is .pivoted an end 51 of a rod 52. The rod 52 carries near the other end thereof two pins 53 and 54. The connecting rod 30 is connected to the rod 52 by means of the pin 53. The pin 54 has pivoted thereon one end of a small lever 55. The other end of the lever 55 is pivoted on a pin 56 which, in turn, is rigidly secured to the lever 35. The center point of oscillation of the pin 54 around the pin 56 coincides with the action of the pin 36.

Although the structure illustrated in FIGURE 2 and described above is the preferred manner of connecting the connecting rods 29 and 30 with the supports 16 and 17, respectively, and the levers 33 and 35, respectively, the required connections could be effected in a manner different from that illustrated in FIGURE 2. Accordingly, reference is made to the schematic showing of FIGURE 3 wherein there is shown clearly by way of illustration another embodiment of the operative connections between the connecting rod 29, the support 16 and the lever 33. A substantially identical arrangement could be provided between the connecting rods 30, the support 17 and ythe lever 35.

In FIGURE 3, the head of the connecting rod 29 is illustrated as consisting of a fork 57 which surrounds the cam 19 of the shaft 20. The other end or foot of the connecting rod 29 is directly pivoted to the arm 40 of the shaft 39 and the lever 33 has a guide 58 in which a pin 59 carried by the connecting rod 29 can slide. The center point of oscillation of the pin 59 within the guide 58 coincides with the axis of the pin 34 which pivotally fastens the lever 33 to the base 2.

It is to be understood that in both of the embodiments of theinvention, the amplitude and the direction of the ihorizontal oscillations of the feed dog 12 and the feed dog 13 within the corresponding slots 10 and 11 of the needle plate 9 depend on the angular position in which the levers 33 and 35, respectively, are rotated with respect to a central or normal position.

The means for operating the lever 33 so as to vary its angular position includes a traditional stitch regulator which can be operated in opposition to a spring 60 which tends to rotate the lever 33 upwardly. The spring 60 is wound on the pin 34 and has its ends anchored to the pin 34 and the base 2, respectively.

The stitch regulator, which is shown by way of example only, consists essentially of an arm 61 rigidly fastened to the pin 34. The arm 61 has pivotally connected thereto one end of a rod 62 with the other end of the rod 62 being pivoted on a lever 63 which, in turn, is pivoted to the upright 3 of the frame of the sewing machine by means of a pivot pin 64. The lever 63 carries a threaded shank 65 on which there is screwed a knob 66 protruding to the outside of the frame of the sewing machine through a slot 67 of the graduated plate 68 which is fastened to the upright 3 in any desired manner.

When the knob 66 is displaced along the graduation of the graduated plate 68, it is possible to stop the knob in any position between the limits zero and four of the graduations of the graduated plate 68. For each of the positions of the knob 66, there is a correspondinggiven angular position of the lever 33 and therefore, a given amplitude of the horizontal oscillations of the feed dog 12. When the knob 66 is displaced downwardly past the zero mark of the graduated plate 68, it is possible to reverse, as desired, the direction of oscillatory movement of the feed dog 12 and thus reverse the direction of feed of the fabric effected by the feed dog 12.

The means for operating the lever 35 so as to vary its angular position includes a stirrup lever 69 of which the arm 70 forms a part with the arm 70 being pivoted to the pin 36 of the lever 35. The stirrup lever 69 has a second arm 71 which is pivoted on the vpin 34- of the lever 33,.

with the pins 34 and 36 being coaxial. The arm 70 is disposed adjacent the lever 35 and has an arcuate slot 72 within which an end 73 of the pin 56 is engaged. A wing nut 74 is screwed onto the end 73 of the pin 56 and firmly connects the lever 35 with the arm 70. A tie rod 75 connects the stirrup lever 69 with a pedal 76 which, in turn, is carried by the support 5 of the sewing machine. By pressing downwardly on the pedal 76, the lever 35 is rotated upwardly about the pin 36 against the action of a spring 77 which acts thereon to rotate it in an opposite direction.

A small plate 78 is secured to the pin 56, and the plate 78 has a surface 79 which is adapted to strike against the wall 80 of the base 2 to thus limit the possible upward rotation of the lever 35 so that the amplitude of the horizontal oscillations of the feed dog 13 cannot exceed a maximum value permitted by the length of the slot 11 of the needle plate 9.

A second small plate 81 is fastened, for instance, to the lower end of a graduated pin 82 which is slidable in a hole 83 of the base 2. The pin 82 is fastened in an adjusted position in the hole 83 by means of a screw 84. The plate 81 is positioned to be engaged by the stirrup lever 69 to limit the possible upward rotation of the lever 35 to values less than the maximum value permitted by the surface 79 in the wall 80.

The spring 77, in accordance with the preferred embodiment of the invention shown in FIGURE 2, is wound on the pin 34 of the lever 33 and has its ends anchored to the lever 33 and the arm 71 ofthe stirrup lever 69, respectively. As `a result of the action of the spring 77, the stirrup lever 69 presses against an extension 85 of the lever 33. The uni-lateral contact between the lever 33 and the lever 35 represented bythe stirrup lever 69 and by the extension 85 permits the knob 66 of the stitch regulator to rotate the two levers 33 and 35 simultaneously, and by the same angular amount so as to vary simultaneously and by the same amount the amplitudes of the horizontal oscillations of the feed dogs 12 and 13.

Once the knob 66 has been fastened in a given position along .the graduations of the graduated plate 68, it is possible to utilize the pedal 76 so as to overcome the resistance of the spring 77 and rotate the lever 35 upwardly with respect to the ylever 33 so as to vary the amplitude of the horizontal oscillations of the feed dog 13 separately from the feed dog 12. The arrangement of the `spring 77 wound on the pin 34 and the anchoring of its ends to the lever 33 and to the arm 71 of the sti-rrup lever 69 has the advantage that the spring 77 and the spring 60 `act independently on the corresponding levers. As a matter of fact, the condition of load of the spring 77 does not vary during the maneuvers carried out on the knob 66 and varies only during the operation of the pedal 76. Conversely, the load conditions of the spring 60 vary upon operating the knob 66 and after the knob has been fastened in position, the load conditions on the spring 6G do not vary during the operation of the pedal 76.

The unilateral contacts between the lever 33 and the lever 35 are adjustable in position with respect to the lever 35. The slot 72 makes it possible to vary the mutual angular position between the stir-rup lever 69 and the lever 35. For this purpose, the surface 79, which is rigidly connected with the pin 56, bears a pointer 86 which cooperates with a visible graduation adjacent the slot 72. When the pointer 86 is opposite the zero mark of the graduations, the unilateral contact between the stirrup lever 69 and the extension 85 of the lever 33 assures parallelism between the levers 33 and 35. Under these conditions, for any position of the knob 66, as long as the pedal 76 is not actuated, the feed dogs =12 and 13 .are subjected to horizontal oscillations of the same amplitude and direction. When however the pedal 76 is actuated, the angular position of the lever 35 with respect to .the lever 33 is `changed to produce a greater amplitude of the horizontal `oscillations of `the feed dog 13, so that the fabric, by the simultaneous action of the two Afeed dogs 12 and 13, is stretched if the feed dog 12 is in front of the .fee/:l dog 13 (FIG. 2) or is curled if the feed dog 12 is behind the feed dog 13. By means o-f the limiter consisting of the plate 811, it is possible to limit the possible amplitude of the oscillations of the feed `dog 13 to a desired value less than that which would be obtained for the contact between plate 78 and wall 80.

When the pointer -86 is dis-placed in one direction or the other with respect to the zero mark tof the graduations adjacent the slot 72, the unilateral contact between the sti-rrup lever 69 and the extension 85 of the lever 33 forces the lever 35 -to assume a position of greater or lesser slope in `one direction or the other with respect to the lever 33. Under these conditions, by moving the knob 66, it is still possible to vary at the same time and by the same `amount the amplitude of the horizon-tal oscillations of the `feed dogs i12 and 13. However, these oscillations will be different 'for the two feed dogs. When the point 86 is moved .towards the minus sign of the scale, the feed dog 13 carries out smaller horizont-al Oscillations than the feed dog 12, so that the fabric is curled if the feed dog I12 is in front of the feed )dog 13 or is stretched if the -feed dog 12 is beh-ind the feed dog 13; vice versa, if the point 86 is shifted towards the plus (-j-) the fabric is stretched `or curled respectively. By acting on the pedal 76, the inclination of the lever 35 is further variable in -an upward Idirection with respect to the lever 33 so -as to vary the horizontal oscillations of the feed dog 13 independently of the horizontal oscillations `of the feed dog 12. When the point `86 is moved towards the minus sign (1 by acting on the pedal 76, the `curl is reduced or removed or the fabric directly stretched or, vice vensa, the tension of the fabric is reduced or removed or the fabric is `directly curled, depending upon whether the feed dog `12 is in front of the feed dog 13 or vice versa; when the point 86 is moved towards the plus sign (-l) Iby acting o-n the pedal '76, the amplitude of the oscillations of the feed dog 13 -is further increased and therefore the Ifabric is stretched more or, vice vers-a, the curl is increased depending on whether the feed dog 12 is in front of the `feed dog -13 or vice versa.

`From the foregoing, it will be readily apparent that there has been provided sui-table structure to accomplish the desired end. Although only a preferred embodiment of the invention has been specifically described and minor modifications have been suggested, it is to be understood that other modifications may be made in the disclosed structure in accordance with the spirit of the invention, as dened by the appended claims.

I claim:

l. In a sewing machine including an arm and a base, a reciprocating needle mounted in said arm, a needle plate on said base and feed dog slots in said needle plate, a differential work feed comprising two supports mounted beneath said base, a feed dog carried by each of said supports and aligned with said feed dog slots, means connected to said supports for naising and lowering said feed dogs in said feed dog slots and a device for controlling the amplitude and direction of horizontal feed oscillations of said feed dogs Within said feed dog slots, said device comprising first and second connecting rods driven by a shaft of the machine, linkages connecting said connecting rods to a respective one of said support, an operator having connections with both of said linkages for reciprocally adjusting said linkages and means separately operable on said linkages to vary the horizontal oscillation of said support, each of said linkages including a lever, said levers being pivotally mounted on aligned pins of the machine, said means operable on said linkages being directly connected to said levers for controlling the angular positions thereof to vary amplitude and direction of horizontal oscillations of said supports.

2. A device according to claim l, wherein said operator is a stirrup having connections with both of said levers for reciprocally adjusting said levers.

3. A device according to claim l, wherein said operator is a stirrup having connections with both of said levers, the connection between one of said levers and said operator being independently adjustable.

4. A device according to claim 1, wherein one of said means operable includes a foot pedal control.

5. A device according to claim 3, wherein the connection between one of said levers land said operator includes a pin in said one of said levers and a slot in said operator, said slot receiving said pin for restricted relative movement in the direction of movement of said operator, and means carried by said pin frictionally connecting said one lever to said opera-tor for normal movement therewith.

6. A device according to claim 1, wherein said one of said levers is operable by one of said means operable including a foot pedal control.

7. The device of claim 5, together with means carried by said pin for limiting movement of said one lever.

8. In a sewing machine including an arm and a base, a reciprocating needle mounted in said arm, a needle plate on said base yand feed dog slots in said needle plate, a differential work feed comprising two supports mounted beneath said base, a feed dog carried by each of said supports and aligned with said feed dog slots, means connected to said supports for raising and lowering said feed dogs in said feed dog slots and a device for controlling the amplitude and direction of horizontal feed oscillations of said feed dogs within said feed dog slots, said device comprising first and second connecting rods driven by a shaft of the machine, linkages connecting said connecting rods to a respective one of said support, an operator having connections with both of said linkages for reciprocally adjusting said linkages and means separately operable on said linkages to vary :the horizontal oscillation of said support, each of said linkages including a lever, said levers being pivotally mounted on aligned pins of the machine, said means operable on said linkages being directly connected to said levers for controlling the angular positions thereof, said operator having connection with said levers, the connection between one of said levers and said operator being independently adjustable, the connection between the other of said levers and said operator including an extension on said other lever engaged by said operator, and spring means acting on said operator to hold said operator in engagement with said extension.

9. A device according to claim 8, wherein the means operable connected to said one of said lever includes a foot pedal control, adjustable stop means for engagement by said operator being apt to limiting the swinging of said foot pedal control.

10. The device of claim 8, together with linkage connected to a stitch regulator and to said operator for positioning said operator in accordance with the position of the stitch regulator.

References Cited by the Examiner UNITED STATES PATENTS 1,602,427 10/ 26 Clayton 112-209 2,341,448 2/44 Knaus 112--209 2,669,205 2/ 5 4 Hayes 112-209 2,782,742 2/57 Hess 112.- 209 JORDAN FRANKLIN, Primary Examiner, THOMAS HICKEY, Examiner, 

1. IN A SEWING MACHINE INCLUDING AN ARM AND A BASE, A RECIPROCATING NEEDLE MOUNTED IN SAID ARM, A NEEDLE PLATE ON SAID BASE AND FEED DOG SLOTS IN SAID NEEDLE PLATE, A DIFFERENTIAL WORK FEED COMPRISING TWO SUPPORTS MOUNTED BENEATH SAID BASE, A FEED DOG CARRIED BY EACH ON SAID SUPPORTS AND ALIGNED WITH SAID FEED DOG SLOTS, MEANS CONNECTED TO SAID SUPPORTS FOR RAISING AND LOWERING SAID FEED DOGS IN SAID FEED DOG SLOTS AND A DEVICE FOR CONTROLLING THE AMPLITUDE AND DIRECTION OF HORIZONTAL FEED OSCILLATIONS OF SAID FEED DOGS WITHIN SAID FEED DOG SLOTS, SID DECIVE COMPRISING FIRST AND SECOND CONNECTING RODS DRIVEN BY A SHAFT OF THE MACHINE, LINKAGE CONNECTING SAID CONNECTING RODS TO A RESPECTIVE ONE OF SAID SUPPORT, AN OPERATOR HAVING CONNECTIONS WITH BOTH OF SAID LINKAGES FOR RECIPROCALLY ADJUSTING SAID LINKAGES AND MEANS SEPARATELY OPERABLE ON SAID LINKAGES TO VARY THE HORIZONTAL OSCILLATION OF SAID SUPPORT, EACH OF SAID LINKAGES INCLUDING A LEVER, SAID LEVERS BEING PIVOTALLY MOUNTED ON ALIGNED PINS OF THE MACHINE, SAID MEANS OPERABLE ON SAID LINKAGE BEING DIRECTLY CONNECTED TO SAID LEVERS FOR CONTROLLING THE ANGULAR POSITIONS THEREOF TO VARY AMPLITUDE AND DIRECTION OF HORIZONTAL OSCILLATION OF SAID SUPPORTS. 